Appearance of enzymes in plasma or urine following renal injury.

The present study evaluates the relevance of plasma enzyme activity in the quantitative assessment of renal injury. In a canine model, enzyme release from kidneys to plasma and urine was studied following an artificial parenchymal enzyme infusion in healthy and ischaemic kidneys. The cumulative enzyme activity in plasma and urine was calculated. Within 1 h of the start of the infusion, 80% of the infused enzyme was recovered in plasma, whereas urinary accumulation was negligible. A similar enzyme distribution between these compartments was obtained if the kidneys were ischaemically damaged before the start of the infusion. Thus enzymes released into the renal cortical interstitium are very rapidly transported to the vascular system and are quantitatively recovered in plasma. Experimental renal infarction revealed that cell death due to ischaemia also resulted in enzyme accumulation in plasma.